MONTEREY BAY, CALIFORNIA — A group of marine biologists managed to capture amazing drone footage of a pod of orcas trying to devour a grey whale carcass, but getting interrupted by a couple of uninvited dinner guests — two humpback whales.

The orca pod has reportedly been on a killing spree in Monterey Bay over the past two weeks, targeting grey whales. The seven whale casualties is oddly high for such a short time span, and it's caught the attention of the scientific community. The orcas’ killing have also caught the attention of the 60-70 humpback whales now in the area, who’ve migrated early this year.

The video shows humpbacks disrupting the orcas during meal time. Orcas are the main predator of grey whales, but humpbacks have no interest in the prey, leading experts to wonder what their motives might be for pissing off their rivals. Rather than a show of altruism in defense of the grey whales, some experts suggest this behavior is more likely to be an instinctual attack response, given that orca pods often go after humpback whale calves.